Characterization of the seismic velocity field and crustal anisotropy in the Marmara region, NW Turkey, using ambient noise

使用环境噪声表征土耳其西北部马尔马拉地区的地震速度场和地壳各向异性

基本信息

批准号：
216043842
负责人：
Professor Dr. Marco Bohnhoff
金额：
--
依托单位：
Sektion 4.2: Geomechanik und Wissenschaftliches Bohren
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2015-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/216043842?language=en
关键词：
Characterization seismic velocity field crustal

项目摘要

Within the here proposed one-year extension of the project we intend to analyze the seismic ambient noise field recorded at the broadband stations surrounding the eastern Sea of Marmara in order to study seismic anisotropy. We intend to apply traditional surface-wave analysis techniques in order to study the azimuthal variation of anisotropy in the region for the first time. The new data provided by GONAF only now allow to conduct such a detailed analysis. We will go beyond previous work (initial two-year phase) not only by analyzing anisotropy but also by refining existing work with denser data including vertical arrays. Studying anisotropy with unprecedented details will also contribute to detect stress accumulations along the Marmara segment of the NAFZ.The isotropic dispersion curves and an average S-wave velocity structure for the region were already derived during the initial phase of this project. Here, we plan to recalculate dispersion curves using all broad-band ambient noise recordings and invert these for anisotropic parameters. This calculation will lead to two principal measurements: the direction of the fast wave and its amplitude as well as the azimuthal dependency of surface-wave velocity. In addition, since we are using surface waves, we will be able to identify the depth of crustal and uppermost mantle anisotropy, which could not be determined in a local anisotropy study using shear-wave splitting. This information will also allow us to elaborate on the origin of the anisotropy in the study region, i.e. stress- or structure-induced. Moreover, P- as well as S-wave velocity models for the region will be refined taking into consideration the anisotropy results allowing for further improved hypocentral precision of local seismicity along the Princes Islands segment offshore Istanbul.

在此处提议的一年延期项目中，我们打算分析马尔马拉海东部周围宽带站记录的地震环境噪声场，以研究地震各向异性。我们打算应用传统的表面波分析技术来首次研究该区域各向异性的方位角变化。 GONAF 提供的新数据现在才允许进行如此详细的分析。我们将超越以前的工作（最初的两年阶段），不仅通过分析各向异性，而且通过使用更密集的数据（包括垂直阵列）完善现有工作。以前所未有的细节研究各向异性也将有助于检测沿 NAFZ 马尔马拉段的应力积累。该区域的各向同性频散曲线和平均横波速度结构已在该项目的初始阶段得出。在这里，我们计划使用所有宽带环境噪声记录重新计算色散曲线，并将其反演为各向异性参数。该计算将产生两个主要测量结果：快波的方向及其振幅以及表面波速度的方位角依赖性。此外，由于我们使用表面波，我们将能够确定地壳和最上地幔各向异性的深度，而这在使用剪切波分裂的局部各向异性研究中无法确定。这些信息还将使我们能够详细说明研究区域各向异性的起源，即应力或结构引起的。此外，该地区的纵波和横波速度模型将在考虑各向异性结果的情况下进行完善，从而进一步提高伊斯坦布尔近海王子群岛部分当地地震活动的震源精度。